Watchcase



Feb; 1, 1955 MQRF 2,700,869

WATCHCASE Filed Jan. 7, 1952 United States Patent WATCHCASE Ernest Morf,La Chaux-de-Fonds, Switzerland ApplicationJanuary 7, 1952, Serial No.265,289

Claims priority, application Switzerland September 28, 1951 4 Claims.(Cl. 58-90) This invention relates to hermetically closed (watertight)watch cases.

Watch cases of this kind as hitherto on the market, are often providedwith a bottom screwed down on the case.

In these cases tight closure of the screwed-on bottom is secured as arule by a packing of compressible material which is inserted betweenthat bottom and the frame of the case. Such cases involve the drawbackthat frequent screwing and unscrewing of the bottom leads to rapid wearof the packing. Another drawback is the necessity of making the bottomof stainless steel (which does not lend itself to ready machining) inorder to avold the influences of transpiration.

It is a well known fact that a piece made of plastic material, forinstance so-called unshatterable glass, can

easily be mounted in a metal frame with altogether satisfactorytightness without the insertion of a special packing. Watch cases haveeven been placed on the market which are provided with a bottom ofplastic material. One drawback of these transparent bottoms consiststherein that they are liable to be damaged when being lifted to open thecase, and their transparency is not fancied by the public which prefersmetal bottoms.

It is therefore an object of this invention to cover entirely by a metalcap a bottom of plastic material which is held in place by friction onthe case frame by means of a border rim of the bottom, the metal capbeing retained on the bottom only.

The advantage offered by this combination of a plastic bottom with ametal cover or cap consists in the fact that the bottom can be impartedany desired appearance, for instance that of the other parts of thecasing, while hitherto one was frequently limited to the use of theparticularly unesthetic stainless steel bottoms on golden, plated orchromed cases.

It is another object of this invention to provide the plastic bottom inone piece with the metal cap, whereby an annular projection of the metalcap is embedded in the plastic material for the purpose of preventing itfrom separating from the metal cap.

Still another object of this invention consists therein that the rim onthe bottom be utilized for the axial maintaining in place of theclockwork within the case.

In the drawings afiixed to this specification and forming part thereoftwo embodiments of the invention are illustrated diagrammatically by wayof example.

In the drawings:

Fig. 1 is a plan view, taken from below and common to all threeembodiments, of a watertight watch case with the bottom mounted in placeon the case.

Figs. 2 and 3 are diametral sections on the line II--II in Fig. 1, eachof them illustrating a different embodiment,

Fig. 2 shows a plastic bottom covered with a metal cap in whichtightness is obtained by a rim flange on the bottom and the case framein which the bottom is held by friction;

Fig. 3 illustrates a metal cap with an annular projection embedded inthe plastic material, this being the preferred form of the invention.Here the clockwork is shown as being held in place in axial direction bythe rim of the bottom.

Referring to the drawings and first to Fig. 1, 1 is the frame of thecase and 14 is a circular ring formed on the lower part of the frame.This case may also be formed with loops to which a bracelet may beattached. The

. 2,700,869 Patented Feb. 1, 1955 ring 14 is formed with twodiametrically arranged semicircular indentations 16 between the twoloops, the purpose of which will be explained farther below.

In the embodiment of Fig. 2 the bottom 3 consists of plastic materialand the frame 1 is formed with a slightly frustoconical wall 2 in whichthe rim 4 integral with the bottom and being shaped in correspondencewith this wall can be compressed. The angle 19 of the rim 4 is so chosenas to facilitate the introduction of the bottom into contact with wall2.

The face of the bottom directed towards the outer surface of the case,when the bottom is seated in place, is covered completely by a metal cap12 held fast on the bottom. The cap 12 is formed with a projecting edge13 which is completely surrounded by the circular ring 14 presenting theindentations 16.

A metal ring 501 is inserted in a ring groove of the rim 3 to reinforceit. The circular ring 14 is so shaped that the projecting edge 13 isaltogether lodged within the interior of the frame, in order that thebottom 3a which provides the tightness of the case, cannot be withdrawnaccidentally without using a special tool.

In order to enable the bottom to be withdrawn when it is desired to openthe case, it is merely necessary to introduce into the indentations 16 atool of corresponding configuration, for instance a long thin blade witha semi-circular projection, fitting the indentations, provided forinstance on one side of the blade. When this tool has thus beenintroduced, a torsional movement may be imparted to it by which axialpressure is exerted on the projection 13. After this tool has beenintroduced into both indentations 16 the bottom can easily be withdrawnfrom engagement with the wall 2a of the frame.

The case of Fig. 4 again shows the slightly frustoconical groove in theframe 1. The plastic bottom 3 is formed with a rim 4 of correspondingconfiguration and a metal ring 5a is provided as a reinforcement for therim which bears against the lower side 6 of a metal lining 7 whichadjusts the clockwork laterally and axially within the casing owing tothe fact that it is itself adjusted with strong friction between thecase frame and the clockwork and that its top extends into contact witha shoulder 8 of the clockwork 9 which it supports in such manner as topress the peripheral edge of the dial 10 against a flange 11 of theframe.

In order to impart to the bottom the metallic appearance desired, forinstance the same as the case proper, it is covered with a metal capwhich is held in position on the bottom only.

In order to firmly secure the plastic material in the metal cap, thismaterial is preferably moulded within the cap by hot-pressing.

In the second embodiment one might also effect the assembly of theseparts by simply setting the cap on the bottom. Since the coeflicients ofthermic expansion of the plastic material and the metal are not strictlythe same, it might happen that the bottom might separate, at least inpart, from the cap which would of course spoil the appearance. In orderto avoid this, an annular projection 20 integral with the cap may beembedded in the plastic material. This projection may be produced byhammering the peripheral part of the metal cap and produce by milling agroove 21 in this part, taking care that the projecting flange 20 extendnormally to the metal cap.

In order to enable the bottom to be taken off without damaging theplastic material, the metal cap may be formed with a peripheral portion13 projecting from the bottom section of the frame. In order, however,to prevent the bottom from being taken off too easily, for instance byway of accident, the projecting portion 13 may be embedded completely inthe interior of the circular ring 14 which is made integral with theframe 1.

Here also semi-circular indentations 16 may be provided in the ring 14.

I wish it to be understood that I do not desire to be limited to thedetails shown and described for obvious modifications will occur to aperson skilled in the art.

I claim:

1. Watchcase comprising in combination, a case frame,

a bottom of plastic material formed with a substantially cylindricalborder flange held by strong friction in said frame, and a metal capfirmly secured to said bottom, said cap having a first flange embeddedin said bottom material and a second flange projecting from saidcylindrical border flange of the bottom.

2. The combination of claim 1, in which the cap flange embedded in thebottom material is a projection of the cap, which extends from the innersurface of this cap, substantially at right angle therewith.

3. The combination of claim 1, in which the outer surface of the borderflange of the bottom is slightly conical as well as the surface portionof the case in which the bottom is engaged and held by strong friction,these two conical surface portions thereby having the same apertureangle and being opened towards the exterior of the case.

4. The combination of claim 3, in which a metal lining is insertedbetween the watch movement and the case, this lining thereby holding themovement in place within the case, radially by contacting twocylindrical surface portions both of the movement and of the case, andaxially by contacting both a shoulder of the movement and the borderflange of the bottom.

References Cited in the file of this patent UNITED STATES PATENTS2,158,044 Haller May 9, 1939 2,446,603 Morf Aug. 10, 1948 2,459,543Schmerheim Jan. 18, 1949 2,547,090 ONeill Apr. 3, 1951 2,621,468 ColombDec. 16, 1952 FOREIGN PATENTS 4,657 Switzerland Feb. 24, 1892 221,351Switzerland Aug. 17, 1942 243,386 Switzerland Dec. 16, 1946 252,576Switzerland Oct. 1, 1948 262,326 Switzerland Sept. 16, 1949 975,724France Oct. 17, 1950

